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CVE-2025-38709

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: loop: Avoid updating block size under exclusive owner Syzbot came up with a reproducer where a loop device block size is change…

Published Sep 4, 2025EPSS 0.15%

Overview

CVE-2025-38709 is a medium-severity vulnerability. It was published on September 4, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

loop: Avoid updating block size under exclusive owner

Syzbot came up with a reproducer where a loop device block size is

changed underneath a mounted filesystem. This causes a mismatch between

the block device block size and the block size stored in the superblock

causing confusion in various places such as fs/buffer.c. The particular

issue triggered by syzbot was a warning in __getblk_slow() due to

requested buffer size not matching block device block size.

Fix the problem by getting exclusive hold of the loop device to change

its block size. This fails if somebody (such as filesystem) has already

an exclusive ownership of the block device and thus prevents modifying

the loop device under some exclusive owner which doesn't expect it.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/139a000d20f2f38ce34296feddd641d730fe1c08Refgit.kernel.org/stable/c/457d2c5e112fd08dc1039b1ae39a83ec1782360dRefgit.kernel.org/stable/c/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624Refgit.kernel.org/stable/c/7e49538288e523427beedd26993d446afef1a6fbRefgit.kernel.org/stable/c/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5

How CyberStrike helps

Frequently asked questions

What is CVE-2025-38709?

CVE-2025-38709 is a medium-severity vulnerability. It was published on September 4, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-38709?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2025-38709?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2025-38709?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2025-38709 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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